结构裂纹损伤的Lamb波层析成像监测与评估研究

Lamb Wave Tomography Technique for Crack Damage Detection

结构健康监测研究中,板壳类结构裂纹损伤监测一直是研究的热点。采用基于相关性分析的概率损伤重构算法(Reconstruction algorithm for probabilistic inspection of damage,RAPID),对结构裂纹损伤监测进行研究。利用RAPID算法中采用信号之间的差异性进行损伤识别和重构,克服了Lamb波复杂多模传播特性对信号分析的影响。在此基础上提出一种改进的RAPID算法,根据裂纹损伤对Lamb波监测信号的反射及散射作用,通过校正损伤区域中裂纹方向上的信号差异系数值(Signal difference coefficient,SDC),强化裂纹方向上的重构图像信息,实现对裂纹损伤的图像重构,并由接收端SDC分布图评估出裂纹的长度。试验结果表明,该方法能较为准确地实现对裂纹损伤的直观图示,重构出的裂纹层析图像能很好地反映裂纹的信息,实现方向及长度的评估,可用于对裂纹损伤的定量评估和扩展监测。

Crack damage monitoring is one of the research hotspot in sstructural health monitoring（SHM） for plate and shell structures. The crack damage monitoring method is studied using reconstruction algorithm for the probabilistic inspection of damage algorithm（RAPID）, which is based on correlation analysis. RAPID algorithm can overcome the shortcomings of the complex signal analysis affected by multimode Lamb wave modes. The improved RAPID algorithm is proposed to reconstruct the tomographic image of the crack damage by correcting the signal difference coefficient（SDC） of the sensing path at the crack direction based on the principle of the Lamb wave reflection and scattering at the crack damages. The direction information of the crack damage can be strengthened. Furthermore, the length of the crack can be evaluated by the SDC distribution map. The experiments are carried out to validate the improved method and the results show that the reconstructed tomographic images can express the crack damage well and can evaluate the direction and length of crack damages. It indicates that the proposed method is useful for crack damage quantitative evaluation and growth monitoring.